Rotary perforating tool and system for well perforation



ROTARY PERFORATING TOOL AND SYSTEM FOR WELL PERFORATION Filed OC'. 2,1968 M. A.'GARR|S0N 3 Sheets-Sheet 1 ggg Sept. 15, 1970 M. A. GARRlsoNROTARY PERFORATINGATOOLAND jsYs'rEM FOR WELL PERFORATION Filed oct. 2,1968- 5 Sheets-Sheet- 2 INVENTOR.r Marion A. Garrison @w @w m ATTORNEYSSept. 15, 1970 M. A. GARRlsoN 3,528,515

ROTARY PERFORATING TOOL AND SYSTEM lFR WELL PERFORTYION Filed oct. z,1968 s sheets-sheet s Il l FIG' INVENTOR.

Mar/'on A. Garrison '.27 Fla.` 9 l 28 United States Patent Olhce3,528,515 Patented Sept. 1970 U.S. Cl. 175--78 10 Claims ABS'I'RAC'I` 0FTHE DISCLOSURE Rotary perforating tool and system for wells havingelectrically powered drilling assembly lowered with elongated tube intowell by flexible cable having insulated electrical conductors, tubeholds said assembly against independent rotation, expanding meansextending through openings in tube for securing and releasing tube atselected locations in well, pump means supplying fluid to the expandingmeans for directing said actions and lubricating a drill bit, a flexibleshaft connecting drill ybit with the upper drill assembly, guide meansfor the flexible shaft, means for applying controlled pressure againstbit while it is rotated, and means for maintaining said tube in a fixedposition in well until bit is withdrawn from perforation.

This invention relates to a system of perforating well casings andadjoining structure by use of a perforating tool and to a perforatingtool utilized in the performance of said system.

Wells frequently are drilled into various types of formation to obtainoil, gas and water, for example. It is the usual practice to line orencase the well bore with casing after the drilling has reached thetotal depth and this involves setting the casing, cementing and thenperforating at one or more locations, which may be on the order ofthirty to forty feet olf bottom.

Sometimes after wells have produced for a period of time, the formationadjoining the well bottom Abecomes clogged or lacking in suiiicientporosity to deliver a desired volume of flow into the well. Anothercondition which requires correction of well bottom features is thefailure of the formation to produce uid in sufficient quantity at theselected level where there has been an indication of capability toproduce the desired quantity at a somewhat higher or lower elevation.Under these circumstances, a length of the casing at the bottom of thewell -will be sealed and it then becomes necessary to perforate thecasing and usually some of the adjoining structural formation to obtaindesired flow of fluid into the well at the newly established level aboveor below the point of sealing.

It has been a custom in the past to provide electric conductor cableextending into the well and gun-type or explosive-type perforators arecarried on the lower end of such cable to the level where perforating isto be undertaken and the circuit controlling means at the surface isthen operated to lire the explosive charges and thereby perforate thecasing and adjoining formation. In many instances, the formations areseriously damaged by the high explosive charges used in such perforatingoperations. The present perforating system has been designed to utilizethe conductive cable heretofore in use and to substitute a new type ofperforating means for the explosive-type perforators and thereby attainthe desired perforating of the:

lower end of the casing and associated formation without shatteringeffect or other damage to the structure.

The present invention includes both a novel system concept and a novelperforator tool concept which represents distinct departures from priorpractices and utilize a number of innovations in attaining the casingand formation perforation. One of these comprises a novel type ofperforating tool inclusive of a drill 'bit carried on a flexible shaftwith provision for continuous rotation of the bit through apredetermined range of drilling movement followed by a withdrawalmovement of the same degree as the extent of the penetration.

Another innovation involves the provision of an elongated tubular bodywhich is supported by conductor cable and lowered into the lwell todispose its lower end at a predetermined elevation with the elongatedtube suspended in spaced relation to the well casing throughout itsentire length and having at least one internal component arranged toextend through openings in the tubular body and engage a surface of thewell casing so as to prevent rotation of the tubular body when thecasing is so engaged. This arrangement leaves the internal components ofthe tubular body free to rotate within its enclosure and thus provide adrive for a bit mounted on a flexible shaft carried at a lower end ofthe string of such internal components.

It is an object of my invention to provide a simple, economical andefficient system for perforating a Well casing and adjoining producingformation to increase ow of formation fluids into the well.

Another object of my invention is to provide a drilling assembly of anovel character contained Within an elongated tubular body adapted to belowered into a well by conductor cable so as to dispose the bottom ofthe assembly at a level of a producing formation and to provide theelectric power requirements for the perforating operations by anelectric motor contained within the tubular body and having theoperation thereof actuating a drilll bit directed by control means atthe surface.

A further object of my invention is to provide a novel type of pump ina` drilling assembly contained within a tubular body lowered into a wellwhich is capable of circulating well fluid or other fluid to expand acontained locking device preventing rotation of the tubular body withinthe well fbore and supplying fluid to a rotating drill bit for thepurpose of lubricating same and washing away cuttings produced by thebit.

'Other objects reside in novel details of construction and novelcombinations and arrangements of parts, all of which will be set forthfully in the course of the following description.

The practice of my invention will be described with reference to theaccompanying drawings illustrating typical structural embodimentsadapted for performing the novel system of perforating well casings andadjoining structure. In the drawings, in the several views of which likeparts bear similar reference numerals,

FIG. l is a vertical section broken at different elevations toillustrate a typical installation in which a drilling assembly issuspended within a well and has its lower end disposed at the level of aproducing formation. The well is shown as having casing extendingthroughout its lengthwise extent and the portions of the drillingassembly disposed between breaks shown in the casing are designated A,B, C, D and E, respectively;

' FIG. 2 is an enlarged fragmentary vertical section of the A portion ofthe drilling assembly which as shown in FIG. 1 is the uppermost portion;

FIG. 3 is another fragmentary vertical section to the same scale as FIG.2 and illustrating the structural features in the B section of theassembly;

FIG. 4 is a section taken along the line y4-4 of FIG. 2;

FIG. 5 is a fragmentary Vertical section of the C portion of thedrilling assembly shown in FIG. 1;

FIG. -6 is another fragmentary vertical section of the portion of thedrilling assembly shown at D in FIG. l;

FIG. 7 is a fragmentary vertical section of the portion shown at E inFIG. l which is the lowermost portion disposed at the level of aproducing formation;

FIG. 8 is a section taken along the line 8 8 of FIG. 7;

FIG. 9 is a fragmentary partially *broken vertical section to the samescale as FIGS. 2 through 8 and illustrates a closed circuit hydraulicsystem which is used in the drilling assembly of the type depicted inFIG. 1 as an alternative for the open circuit hydraulic system of thatassembly;

FIG. l() is a section taken along the line 10-10 of FIG. 2; and

FIG. 11 is a section taken along the line 11-11 of FIG. 9.

The practice of my invention will be described first with relation tothe form of drilling assembly illustrated in FIGS. 1 through 8 and 10 inwhich an open circuit hydraulic system is provided for use of well fluidonly. As shown in FIG. l, a well 21 has been shown as extending from thesurface 22 to a lower producing formation 23 with the well bore encasedby casing 24, and electric conductor cable 25 connected with means 26 atthe surface controlling a circuit through said cable suspends a drillingassembly designated generally by the reference numeral 27 interiorly ofthe well casing in spaced relation thereto with a string of componentscomprising the drilling assembly being shown in the portions A, B, C, Dand E of FIG. 1 in outline form and in complete detail in other figuresof the drawings as will be specifically set forth in the followingdescription. The conductor cable 25 carries electric current to theelectric motor 30 driving a lower perforating tool 80 to provide therequired drive therefor. This motor is a single phase motor and thecircuit is completed by grounding the motor 30 to the drilling assembly27 as shown at 31 in FIG. 2. This ground 31 is connected to the outersteel portion of the conductor cable 25 and therefore completes theelectrical circuit. When the conductor cable has sufficient insulatedconductors to handle three phases, a multi-phase motor may be used.

The structural arrangement shown in FIG. 2 includes an elongated bodyportion 32 secured by a top cover member 33 which is shouldered as shownat 34 and provides a seat for an internal threaded portion terminatingin an annular flange 35 which seats against the shoulder 34 and suspendsbody portion 32 and a depending tubular portion 36 in the well bore. Theelectric conductor cable 25 is connected to and extends through thesubmerged top portion and forms a casing for the connector motor leads25a and 25b which extend through the hollow portion of the tubularenclosure 36 and into the threaded neck and bore 30a of a motor 30. Aswill be best understood by reference to FIG. 10, a channel 37 is formedin the exterior wall of the motor assembly 30m and permits the leads todescend to the bottom of said motor as shown at the top of FIG. 3.

As shown in FIG. 3, a collar portion 40a extends downwardly from thebase of motor 30 and an internal coupling `41 extends downwardly fromthe throat 40C within a compensating tube 42 having a protector 43 atits top and a plug 44 adjoining the protector. An elongated flexibletube portion 42a of tube 42 is contained within an annular bore 45 belowthe plug 44 and is filled with oil, its lower end connecting to theinterior of a sealed housing of the adjoining gear reduction unit 40while its opposite end is plugged. A spring coupling 50 connects theextended portion of coupling 41 with the input shaft '51 of thereduction gear assembly `40 and a Woodruff key 52 holds the coupledmembers against an unwinding action. The gear reduction unit 40 has adouble oil seal assembly 53 at its upper end and a retaining ring 54under the seal assembly 53 which is disposed at the upper end of adouble ball bearing assembly 55 interiorly of the upper section 56a ofthe gear reduction housing 40. A compression tube 57 conducts oil fromthe compensating tube `42 to an outlet 57x lubricating the bearingassembly 55 and input shaft 51.

A pinion gear '60 is mounted on the lower end of input shaft 51 anddrives an intermediate shaft 61 of the gear assembly which is connectedat its lower end with an internal gear 62 which drives the output shaft63 of the gear reduction assembly. In this arrangement, the shafts 51and 63 are centered on the longitudinal axis of gear 62. Intermediateshaft 61 and output shaft 63 are each supported yfor rotation by ballbearing assemblies `64 and 65 and oil seals 66 are disposed below thelower ball bearing assembly 65 and secured by retaining rings `67 whilean O-ring 68 is disposed in a recess in the outer wall of the lowersection 56e of the reduction gear housing to confine lubricant flow in amanner to be subsequently described.

As shown in FIG. 5, the elongated tubular body 36 of drilling assembly27 has a slotted portion 70 adjoining expanding means in tube 36 havingan exterior portion arranged for movement through the slot 70 intofrictional engagement with casing 24 to prevent rotation of tube 36relative to casing 24. The expanding means shown in FIG. 5 comprises aslip body 71 of tapering cross section supported by a screw attachmentwith an adjoining portion of tubular body 36 and bearing against a slipcarrier 73 on which a slip 74 is secured by cap screws 75. Slip pins 76secure links 77 to a piston 78 mounted on a sleeve 79 on drive shaft 72.The sleeve 79 confines an elongated spring 83 in biasing relation topiston 78. Slip 74 as shown in FIG. 5 includes a plurality of jaws withteeth 74a on their exterior surface which are disposed at a commonoblique angle to the longitudinal axis of slip 74 causing an expansionof said jaws when moved in one direction and a contraction by oppositemovement. Because of the taper of body 71, slacking of cable 25 inducesretraction of the slip jaws and spring pressure against piston 78 holdsthe jaws in retracted position until the next drilling cycle.

Piston 78 is hollow and confines the top plate 85 of a low pressure pumpassembly 84 carried on driven shaft 72 and a top bearing 86 is providedfor plate 85 which is connected to a lower plate 87 having a bearing 87aby screws 88 and the pump impeller 89 is disposed between said platesfor rotation directed by a pump shaft 90 which is secured on drivenshaft 72 by a key 91. Packing 92 is held against shaft 90 by a nutmember 93 which is secured against unfastening by a lock nut 94. Thisprovides a sealed arrangement for the internal bearing means permittingthe hub of the piston to rotate independently of its outer portion.

Pump assembly 84 will by-pass fiuid within itself if the pressurereaches approximately 35 lbs. per square inch above the normalhydrostatic pressure within the well 21. The pump is driven by means ofthe sliding keys 91 in the keyway 72x of driven shaft 72. As pumpassembly 84 is fastened fixedly -with the tubular portion 36, as shownat 82, it does not move up and down with the motor reduction gear unit40.

A fiuid relief valve 96 comprising an upper hollow section 96a and alower hollow section 96b has a threaded connection 97 with the lower endof shaft 72 which terminates at said connection. A keyed shaft 98 isfastened to the interior surface of upper section 96a by keys 98a and isheld in driven relation by relief valve 96. A retaining ring 99 andwasher 100 separate the hollow interior of section 96a from the hollowinterior of section 96h which confines a spring 103, permittingelongation of the valve when the conductor cable raises, therebyexposing port to permit fiuid flow out of the cylinder above piston 78.Tubular portion 36 makes a threaded connection 101 with an exterior wallportion of a hollow chamber 102 in which the relief valve 96 is located.

A thrust type ball bearing assembly is mounted on shaft 98 below valve96 and has an enlarged intermediate portion 111 of its exterior surfacein close fitting engagement with tubular portion 36 and an O-ring 112therein prevents fluid flow along the interior of said tube 36 pastenlarged portion 111. Assembly includes an upper oil seal unit 113 and alower oil seal unit 1114, secured by retaining rings 115 and 116,respectively. A plug 117 normally closes an opening by which a lubricantcan be introduced into an interior space 118 for supplying the lubricantrequirement of an upper ball bearing unit 119 and a lower ball bearingunit 120.

FIG. 6 illustrates an assembly 125 having a threaded connector 126inserted between spaced threaded portions of tubular member 36, thelowermost of said sections having a plate 127 closing its hollowinterior and supporting a hollow guide tube 128 which extends upwardlyin enclosing relation to the lower end of keyed shaft 98 which has aninternal coupling 129 with a exible shaft 130.

FIG. 7 illustrates the perforating assembly of perforating tool 80 whichincludes an extension of guide 128 being supported within tubularportion 36 by another plate 132 supported from its inner wall surfacesand having a welded connection with guide 128. The lower end 36x oftubular portion terminates in a threaded connection 133 with anelongated body 134 having an internal bore 135 extending from the lowerend of shaft at its top to a bottom side outlet 136 in a curved path.Preferably, the body 134 is formed by two castings providing therequired shaping and held as an integral body by screws 137.

The lower end of flexible shaft 130 is part of a stretch of flexibleshaft shown at 138 extending through curved bore 135 which acts as aguide therefor. A drill bit 139 is carried at the lower end of flexibleshaft and extends outwardly beyond outlet 136 to perforate the wellcasing '24 and associated producing formation 23. Flexible shaft 138 hasan internal passage 140 (FIG. 8) preferably lined by plastic tubingwhich delivers a lubricant to the drill bit while operating and alsoprovides a sufficient ow to wash cuttings from the perforation beingformed. A casing shoe 141 secures the headed ends of lower screws 137against damage during drilling and is held on body 134 by cap screws142.

For some operating requirements, it will be advantageous to provide aclosed circuit lubricating system in the drilling assembly and a closedcircuit system of this type has been illustrated in FIGS. 9 and ll. Thelubricant circulation and pumping and distributing features includedifferent structural arrangements than those shown in FIGS. 5 and 6 anddescribed hereinbefore and have been given different reference numerals.Structure shown above and below the closed circuit hydraulic system ofFIG. 9 is identical with that shown in FIG. 5 and has been given thesame reference numerals as in FIG. 5.

The closed circuit hydraulic system 144 illustrated in FIG. 9 has apiston 145 mounted on a lower portion of shaft 72 andy the pistonencases the top plate 146 of a pump assembly and a bottom plate 147 isspaced therefrom. A top bearing 148 is provided for plate 146 and alower bearing 149 is supported adjacent plate 147. The plates aresecured by screws 150 and an impeller 151v on shaft 72 rotates in thespace between plates 146 andl147. Packing 152 is secured in a nut 153 atthe lower end of bearing 149 and a lock nut 154 seats on nut 153 tomaintain its established locked position.

A threaded connector 155 is disposed between spaced sections of tubularportion 36 and has an internal passage 159 through which lubricant iselevated into the hollow interior of impeller 151 and thence into piston145. In this system, it is necessary to conserve oil and it is bypassedthrough a passage 161 in the shaft 158 and out of a port when theconductor cable or wire line 25 lifts the tool, thereby uncovering port160 and flows into the piston relieving pressure above the piston,allowing the piston to be raised to the top of its stroke when a liftingforce is exerted by cable 25.

System 144 has a flexible reservoir 162 of soft, resilient oil-proofmaterial which is exposed to the hydrostatic pressure in the well 21 bybeing located outside the housing 163 of system 144. Reservoir 162 willexpand and contract sufciently to accommodate 'the displacement flow ofthe piston which actuates the slip 74, and also permits a moderateamount of leakage. As the piston which drives the bit into drillingcontact moves down, the oil below same is displaced into the reservoir162 through ports 159 located in the cylinder near the lower end ofsame. When the assembly is lifted by wire line 25, the valve 156 opensto allow the oil above the piston to be displaced as stated above. Aball bearing assembly is mounted on shaft 158 below the pump assembly 84and comprises upper and lower oil seals 164:1 and 164b, respectively,and upper and lower bearings 165 and 166, respectively.

A lower pump assembly is provided to circulate well Huid to the bit andis of small volumetric output. This pump has an upper plate 171 securedon shaft 158 by a nut .172 and lock nut 173 and a screen member 174 isdisposed between upper plate 171 and lower plate 175 having a passage176 for delivery of screened well fluid into a lower distributingchamber 177 of the pump. Screen member 174 and associated lower plate175 extend across the entire interior of tubular portion 36 withopenings 178 or ports in portion 36 permitting intake of well fluidthrough screen member 174, thence through passage 176 into the interiorportion of chamber 177 under the pumping action of rotor 185 (FIG. l1).

The arrangement of the bottom closure of chamber 177 is the samestructural arrangement as shown in FIG. 6 and connects in turn with aperforating tool of the type shown in FIG. 7. Consequently, referencenumerals shown in FIG. 6 have been applied to the bottom plate 127 andguide structure 128 shown in FIG. 9. A slight gap 179 is providedbetween the top of guide member 128 and the lower end of shaft 158 whichpermits the well fluid within chamber 177 to pass into an internalpassage 181 in the pump rotor 180 and thence into keyed shaft .130 towhich the flexible shaft 138 of the perforating tool is connected.

It will be apparent that the well fluid after screening to eliminatesolids which might block internal passages through which the uid isconducted is delivered to the drill bit of the perforating tool insufficient volume to provide the desired lubricating effect and toremove cuttings from the bit, while the lubricant circulation throughthe remainder of the closed circuit hydraulic system 144 is a cleanlubricant which is conned and circulated 1taihrough the closed circuitwithout contamination by well i uid.

Again referring to FIG. l in which the entire drilling assembly is shownas being in an operati-ve position within an oil well 21, said assemblyis shown in portion A and the related view, FIG. 2, as having an uppermember providing connection with electric conductor cable extending intothe well from a surface location outside of same and with control meansat the surface for controlling the operation of an electric circuitthrough and inclusive of said conductor cable. An electric motor isdisposed in the upper body portion 32 within an elongated tubular body36 which extends throughout substantially the entire length of drillingassembly 27, the lower portion of which is disposed in a perforatingposition at the bottom of well 21. Motor 30 is connected in drivingrelation to an input shaft 51 which as shown in FIG. 3 extends into agear reduction unit 40 and another output shaft 63 extends downwardlyfrom the lower end of the gear reduction unit in coupled relation to adriven shaft 72. The tubular body 36 is apertured or slotted as shown at70 in FIG. 5 and an expanding locking device has a slip portion 74 andassociated carrier and linkage which assist the expansion andcontraction movements of the slip -body through the slot 70 intogripping engagement with the well casing 24.

A sleeve 79 surrounds shaft 72 in supporting relation to the slipassembly which is fastened to tubular portion 36 by screws or othersuitable fastening means. A low pressure pump assembly 84 is mounted onshaft 72 below the slip assembly and has an upper piston which is drivenby the electric motor-reduction gear unit. The piston is subjected topump pressure and well fluid pressure and is the means which controlsthe expanding and closing movements of the slip assembly. When the slipis expanded into contacting relation with the well casing, rotation ofthe elongated tube member within the well is prevented but the internalcomponents of such assembly are rotated to accommodate the perforatingtool in a manner which will be described hereinafter.

A pump unit is carried on shaft 72 immediately below piston 78 anddirects the ow of well fluid admitted into the interior of tubularmember 36 by the slotted openings 70 and circulates such flow downwardlythrough a hollow portion of the shaft and into the bore of a connectingflexible shaft is a part of the perforating tool assembly. In theoperation of the drilling assembly, provision is made for lowering theinternal components a predetermined distance during one perforatingcycle and after completion of which, the assembly is again raised byactuation of the conductor cable to dispose it in the operative positionto resume the next drilling cycle.

The perforating tool assembly 80 as shown in FIG. 7 incldes a tubularbody extending downwardly from plate 132 in encompassing relation tokeyed shaft 130 which is connected to the flexible shaft 138 extendingthrough a curved internal bore in the elongated body 134 and whichcarries a drill bit 139 at its lower end extending through a bottom sideoutlet 136. The guide 128 prevents excessive bending or twisting oftlexible shaft 138 within it and within the bore 135 while the bit 139is being rotated and drilling a perforation through the well casing oradjoining formation. It also is essential that the bit and exible cablebe held against twisting during the following retraction stage of thecycle and the pumping pressure exerted against piston 78 and associatedcomponents is continued in the same degree until the bit is completelyretracted and resumes the position shown in FIG. 7. At that stage of theoperation, the conductor cable is pulled, allowing the relief valve 96to move upwardly on shaft 72, exposing the opening 95 which it normallycovers, thereby allowing confined well fluid to pass out of shaft 72relieving pressure on the top of piston 78 and the resulting upwardmovement retracts slip 74, allowing it to return within the enclosure oftubular body 36 so that the entire assembly is elevated a distanceequivalent to the maximum extension of bit 136 in the drilling action toestablish a new position for operating in the next drilling cycle.

I claim:

1. A system for drilling perforation holes in a bordering surface of awell bore at a producing formation level, comprising an electricconductor cable supported at the surface and maintained in a dependingposition within the well bore, means at the surface for controlling anelectric circuit through said cable, an elongated tube suspended by saidcable in the well bore at a selected elevation below the surface, anelectrically powered drilling assembly means for drilling theperforation holes, the electrically powered drilling assembly meansbeing suspended by said cable interiorly of the tube and secured by thetube against independent rotation, pressure responsive expanding meansextending through openings in the tube for selectively securing andreleasing the tube at selected locations in said well bore, and a pumpmeans for supplying fluid pressure to the expanding means whereby todirect its securing and releasing actions.

2. A system as defined in claim 1, having means for limiting the outputpressure of the pump means.

3. A system for drilling perforation holes in a bordering surface of awell bore at a producing formation level, comprising an electricalconductor cable supported at the surface and maintained in a dependingposition within the well bore, means at the surface for controlling anelectric circuit through said cable, a drilling assembly supported bythe conductor cable for rotation in a depending position in the wellbore and including an elongated tubular enclosure for a drive assembly,and a perforating tool connected `with the drive assembly, saidperforating tool being directed in a laterally directed drillingoperation by rotation imparted by the drive assembly responsive to thecontrol means at the surface, said drive assembly including an electricmotor, pressure responsive means for selectively locking the tubularenclosure to the well casing at selected depths within the well, pistonmeans connected to the perforating tool for applying pressure to the bitthereof during the drilling operation, and pumping means operable toselectively supply fluid pressure to the locking means and the pistonmeans whereby to selectively lock the tubular enclosure to the wellcasing and apply pressure to the bit of the perforating tool.

4. A system as defined in claim 3, including second pumping means withinthe tubular enclosure for supplying uid to the drill bit to lubricate itand wash away cuttings from the perforation, and means for supplyingsaid second pumping means with a fluid withdrawn from the well bore.

5. A system as defined in claim 3, having an open circuit hydraulicsystem including second pumping means within the tubular enclosuresupplying liquid to the drill bit to lubricate it and wash cuttings awayfrom the perforation, and means for supplying iiuid from the well boreto said hydraulic system.

6. A system as defined in claim 3, having a closed circuit hydraulicsystem including said rst pumping means for circulating clean lubricantthrough the system, and a second pumping means within the tubularenclosure for supplying fluid from the well bore to lubricate the drillbit and wash cuttings away from the perforation.

7. A system for drilling perforation holes in a bordering surface of awell bore at a producing formation level, comprising an electricconductor cable supported at the surface and maintained in a dependingposition within the Well bore, means at the surface for controlling anelectric circuit through said cable, a drilling assembly in the wellbore supported by the conductor cable and including an elongated tubularmember containing an upper drive assembly inclusive of an electricmotor, a gear reduction unit associated with the motor having concentricinput and output shafts, pressure responsive expanding means extendingthrough openings in the tubular member for selectively securing andreleasing the tubular member at selected locations in the well bore,pump means operable by said motor for supplying tluid pressure to theexpanding means whereby to secure the elongated tubular member atseletced elevations within the Well bore, and said pump means being alsooperable to circulate a lubricant fluid interiorly 'of said driveassembly, and a lower perforating tool having a flexible shaftconnection with the output shaft of the upper drive assembly, saidperforating tool having a drill bit directed in a laterally directeddrilling operation by rotation of the output shaft responsive to thecontrol means at the surface, a guiding mechanism for said flexibleshaft, said drilling assembly including means for measuring the travelof the conductor cable while the perforation is being cut by said bit,said expanding means being operable to continue to hold the guidingmechanism of the perforating tool against movement while the bit iswithdrawn from the perforation, means delivering a lubricant uid ininduced flow through the exible shaft to said bit, piston meansresponsive to said pump means and connetced to said perforating tool forapplying a controlled pressure against the bit while it is rotated, andmeans for returning the conductor cable to the same starting position atthe beginning of each cutting cycle.

8. In combination with a system for drilling perforation holes in thebodering surface of a well bore wherein a drilling assembly depends insaid well bore from an electric conductor cable supported at thesurface, said drilling assembly including an elongated tubular membercontaining a drive assembly and a perforating tool, the improvementwhich comprises:

pressure responsive expanding means mounted on said tubular member forengaging said well bore whereby to secure said tubular member atselected depths in the well; and selectively operable pump means forsupplying fluid pressure to said expanding means whereby to selectivelyoperate said expanding means. 9. The invention recited in claim 8,wherein: said tubular member has at least one slot therein for receivingsaid expanding means; and said expanding means comprises:

jaw means slidably mounted in said slot to be selectively movable awayor towards the axis of said tubular member, said jaw means being forengaging said well bore; and a tapered actuating mechanism mounted alongthe axis of said tubular member in sliding contact with said jaw means,said actuating mechanism being operable in response to the fluidpressure of said pump means to move said jaw means into engagement withsaid well bore.

10. The invention recited in claim 8, including pressure responsivemeans connected to said perforating tool for applying pressure to thebit thereof during the drilling operation, said pressure responsivemeans being responsive to the iluid pressure of said pump means.

References Cited UNITED STATES PATENTS 2,516,421 7/1950 Robertson 175-782,539,047 1/1951 Arutunofl 175-78 X 2,558,452 6/1951 Mennecier 175-782,631,821 3/1953 Caldwell 175--78 ERNEST R. PURSER, Primary ExaminerU.S. C1. X.R. 175--99

